The present invention relates to an ink jet recording apparatus in which a plurality of recording modes which set respectively a different correspondence of gradation data and the ink amount of a dot are prepared and these recording modes are applied selectively.
As a typical ink jet recording apparatus (hereinafter simply referred to as a recording apparatus), a printer and a plotter are known well. In this recording apparatus, for example, a drive signal in which a plurality of drive pulses are connected in series is generated. Printing data including gradation data is transmitted to a recording head, and the necessary drive pulses are selected from the drive signal on the basis of this transmitted printing data and supplied to a piezoelectric vibrator. Hereby, the amount of ink droplets ejected from a nozzle orifice is changed according to the gradation data.
For example, in a printer that sets four gradations including non-recording printing data (gradation data 00), small-dot printing data (gradation data 01), middle-dot printing data (gradation data 10), and large-dot printing data (gradation data 11), the ink droplets that are different in the amount according to the respective gradations are ejected. Further, a plurality of recording modes are prepared, which respectively set a different correspondence of gradation data and the ink amount of a dot, and drive control in which the plurality of recording modes are selectively applied is performed. For example, speedy recording is performed by applying a high-speed recording mode in which a dot having the comparatively large diameter is recorded, or recording of higher image quality is performed by setting a high-resolution recording mode in which a dot having the comparatively small diameter even in the same gradation data is recorded. Hereby, this printer corresponds to various requests.
On the other hand, the thickness of a recording sheet on which an image is recorded is various so that plain paper is about 0.1 mm in thickness, a postal card is about 0.26 mm in thickness and board paper is about 1.2 mm in thickness. Therefore, an adjustment mechanism for changing a distance (platen gap) between a platen for guiding the recording sheet and the recording head is provided. This adjustment mechanism is generally constituted so as to move the recording head up and down, and it sets a gap from a nozzle orifice of the recording head to a surface of the recording sheet in the predetermined range.
Recently, a recording apparatus is also considered, which has a border free print mode in which printing is performed throughout all the area of four sides of the recording sheet. In this recording apparatus, data to be printed in a range that is wider a little than the width and length of the recording sheet is prepared and ink droplets are ejected up to the region over the four sides. Then, in this recording apparatus, the ink droplets ejected to the outside of the four sides of the recording sheet are absorbed by an absorber provided in the corresponding position on the rear surface of the platen.
Recently, greater improvement of image quality is requested for the recording apparatus. In order to correspond to this request, it is necessary to reduce further the diameter of a recording dot, that is, to reduce the amount of the ink droplet. However, in case of employing a minute ink droplet (referred to as a super-minute ink droplet for convenience of description), of which the amount of ink is about 2 pL (picoliter) that is extremely small, viscous resistance of air makes a great influence. Therefore, it is difficult for the super-minute ink droplet to obtain the required jet speed, and in case that the distance from the nozzle orifice to the recording sheet is large, it is difficult to cause the ink droplet to reach the recording sheet. Particularly, in case that the platen gap is set large by the above platen gap adjustment mechanism, it is more difficult to cause the ink droplet to reach the recording sheet.
Further, though it is necessary to cause the ink droplet to reach the absorber in the border free print mode, since this absorber is provided on the rear surface of the platen, the distance from the nozzle orifice to the platen is farther than the distance from the nozzle orifice to the recording sheet. Therefore, it is difficult to cause the absorber to absorb the super-minute ink droplet.
In view of these circumstances, an object of the invention is to provide an ink jet recording apparatus that can prevent a super-minute ink droplet from becoming misty.
In order to solve the aforesaid object, the invention is characterized by having the following arrangement.
(1) An ink jet recording apparatus includes:
a recording head for ejecting an ink droplet from an nozzle orifice according to supply of a drive pulse to a pressure generating element;
a recording node setting unit for setting a recording mode from a plurality of recording modes that are different in a correspondence of gradation data and amount of ink;
a drive signal generator which can generate various kinds of drive signals including drive pulses according to the recording mode, wherein the drive signal generator generates the drive signal according to the recording mode set by the recording mode setting unit, and the drive pulse extracted from the generated drive signal is supplied to the pressure generating element;
a gap detector for detecting a platen gap from the nozzle orifice: and
a recording mode limit unit for limiting usable recording modes to a part of the plurality of recording modes according to the platen gap detected by the gap detector.
(2) An ink jet recording apparatus comprising:
a recording head for ejecting an ink droplet from an nozzle orifice according to supply of a drive pulse to a pressure generating element;
a recording mode setting unit for setting a recording mode from a plurality of recording modes that are different in a correspondence of gradation data and amount of ink;
a drive signal generator which can generate various kinds of drive signals including drive pulses according to the recording mode, wherein the drive signal generator generates the drive signal according to the recording mode set by the recording mode setting unit, and the drive pulse extracted from the generated drive signal is supplied to the pressure generating element;
a recording mode limit unit for limiting usable recording modes to a part of the plurality of recording modes when a border free print mode in which printing is performed up to borders of a recording sheet is set.
(3) The ink jet recording apparatus according to (1) or (2) further comprising:
a recording mode switching unit for switching the recording mode to one of usable recording modes judged by the recording mode limit unit when the recording mode set by the recording mode setting unit is not the usable recording mode.
(4) The ink jet recording apparatus according to any one of (1) to (3) further comprising:
a notice unit for notifying that the recording mode set by the recording mode setting unit is not suitable when the recording mode limit unit judges that the recording mode set by the recording mode setting unit is not suitable.
(5) The ink jet recording apparatus according to (4), wherein the notice unit notifies that the recording mode is not suitable by sending an error code to a host computer.
(6) The ink jet recording apparatus according to any one of (1) to (5), wherein inks ejected respectively by h the various kinds of drive signals generated by the drive signal generator are different in the minimum amount.
(7) The ink jet recording apparatus according to (1), wherein the recording mode limit unit limits the usable recording modes to a part of the plurality of recording modes when a border free print mode in which printing is performed up to borders of a recording sheet is set.
(8) The ink jet recording apparatus according to (2) further comprising:
a gap detector for detecting a platen gap from the nozzle opening,
wherein the recording mode limit unit limits the usable recording modes to a part of the plurality of recording modes according to the platen gap detected by the gap detector.
(9) An ink jet recording apparatus includes:
a recording mode setting unit for setting a recording mode from a plurality of recording modes that are difference in a correspondence of gradation data and amount of ink;
a drive signal generator for generating a drive signal selected from various kinds of drive signals according to the recoding mode set by the recording mode setting unit;
a recording head for ejecting an ink droplet from an nozzle orifice thereof according to the drive pulse; and
a recording mode limit unit for judging whether the recording mode set by the recording mode setting unit is a usable recording mode for recording.
(10) The ink jet recording apparatus according to (9) further comprising a gap detector for detecting a platen gap from the nozzle orifice, wherein the recording limit unit judges whether the recording mode set by the recording mode setting unit is au sable recording mode for recording according to the platen gap detected by the gap detector.
(11) The ink jet recording apparatus according to (9) or (10), wherein the recording limit unit judges whether the recording mode set by the recording mode setting unit is a usable recording mode for recording according to whether a border free print mode in which printing is performed up to borders of a recording sheet is set or not.
(12) The ink jet recording apparatus according to any one of (9) to (11) further comprising:
a recording mode switching unit for switching the recording mode to one of the usable recording modes when the recording mode set by the recording mode setting unit is not the usable recording mode.
(13) The ink jet recording apparatus according to any one of (9) to (12) further comprising:
a notice unit for notifying that the recording mode set by the recording mode setting unit is not the usable recording mode when the recording mode limit unit judges that the recording mode set by the recording mode setting unit is not the usable recording modes.
(14) The ink jet recording apparatus according to (13), wherein the notice unit notifies that the recording mode is not the usable recording mode by sending an error code to a host computer.
(15) The ink jet recording apparatus-according to any one of (9) to (14), wherein inks ejected respectively by the various kinds of drive signals generated by the drive signal generator are different in the minimum amount.
The present disclosure relates to the subject matter contained in Japanese patent application No. 2000-316256 (filed on Oct. 17, 2000), which is expressly incorporated herein by reference in its entirety.